Pilot operated pneumatic valve

A pilot operated valve assembly comprising:

• a valve body having a pressurized air supply inlet port in communication with a source of pressurized air, and at least one cylinder passage;
• a main valve bore extending axially through said valve body to present a pair of open ends, a pair of retainer assemblies threadably received in said pair of open ends of said main valve body to close same wherein each of said pair of retainer assemblies define an innermost terminal end, and a main valve member defining a spool valve having a pair of opposed annular valve heads disposed at either end of said spool valve, said main valve member movable between predetermined positions within said main valve bore to selectively direct pressurized air from said inlet port through said at least one cylinder passage;
• a pilot valve bore formed within and extending through said main valve member coaxially relative to said main valve bore to present a pair of open ends at said pair of opposed valve heads, each of said pair of opposed valve heads defining an outer diameter moveably received in sealing engagement with said main valve bore and an inner diameter moveably and sealingly disposed about a corresponding one of said innermost terminal ends of said pair of retainer assemblies;
• a pair of short pilot cylinder ports defined in said pair of retainer assemblies and spaced apart from one another, said pair of short pilot cylinder ports extending between said main valve bore and said pilot valve bore so as to provide fluid communication between said main valve bore and said pilot valve bore;
• and
• a pilot valve member movable between predetermined positions within said pilot valve bore to selectively direct air from said pilot valve bore through alternating ones of said pilot cylinder ports to act upon said main valve member thereby moving said main valve member between said predetermined positions.